Method of preparing dull artificial silk



Patented Feb. 16, 1932 UNITED STATES PATENT OFFICE COBNELIB WABNARDUS ZAHN, OF HELMOND, NETHERLANDS, ASSIGNOB; T0 NAAMIJOOZ E I VENNOOTSCHAP: J. A. CARPS GARENFABRIEKEN, OF HELMOND, NETHERLANDS mentor) or rnnranme No Drawing. Application filed, m 31, 1929, Serial The invention relates to a method of preparing dull artificial silk, from cellulose esters, such as acetate silk, and especially from regenerated cellulose, such as viscoseand ammoniacal copper oxide silk..

For obtaining a dull lustre of artificial silk various methods are applied.

1. The spinning solution, e. g. the viscose solution, is prepared with some ingredient, which causes the spun thread to look dull. In this case the dull lustre is inherent to the fibre. The chemicals used form a homo- 1geneous mixture with the regenerated celluose.

2. The normally prepared spinning solution is spun andthe silk obtained is submitted to a subsequent treatment which causes a precipitate to settle on the fibre, causing the silk to look dull. This precipitate may consist of an insoluble salt, e. g. an inorganic salt like barium sulphate or an organic salt, such as fatty acid salts of aluminium.

3. The fibre is submitted to aswelling process by means ofconcentrated sulphuric or phosphoric acid, chloride of zinc, and such like substances.

4. The fibretis impregnated with titanic salts, upon which the bath is heated; finally the titanic salt is converted into hydroxide by means of heating in an autoclave.

According to the invention it has been found that a lasting aftertreatment which, like the method mentioned sub 4 is based on ahydrolysis, may be obtained by treating the silk with a solution of suitable silicofluorides in water which are capable of separating silicic acid when heated. A very suitable silicofluoride for this purpose is magnesiumsilicofluoride (MgSiF tSH O). This silicofluoride is easily soluble in cold water (1:1.5) and gradually separates silicic acid when heated, the silicic acid being dissolved again after cooling.

Now this process is based on the principle that the silicic acidseparated by heating is partly incorporated into the silk, in such a. way that it cannot be washed away, when the silk is rinsed with water, or treated with diluted acids or soap solutions.

DULL ARTIFICIAL sILIr The silk to be treated is introduced into a cold solution of the silicofluoride; then the temperature of the bath is gradually raised.

After a sufficiently long time the silk is taken from the bath, and thoroughly rinsedLwith water. The resulting silk can immedlately be dyed or dried.

The product obtained in this way is a dull, milky white silk, which may easily be moistened, and submitted to a further treatment.

' The silk has decreased about 110% in strength but this may be remedied to a certain extent by adding a little ammonia to the silicofluoride solution. This results moreover in the solution'being quite clear again, when cooled down, and it may then be used for a following treatment. \Vhen rinsed with Water, and

treated with diluted acids the silk is very resistent. It is sufficiently proof against soap solutions of 5060 C. 4

The dull silk obtained according to themvention is, however, not quite proof agalnst a hypochlorite solution, as by a treatment oi: the silk with such a solution the lustre is partly restored.

The circumstance that the treatment may be effected in one single bath and that the silk need only be slightly manipulated, is a great advantage of the process described, and

is very useful at the moment of sorting.

The process is illustrated by the following example:

100-400 g. of magnesium silicofluoride are dissolved in 10 L. of cold water. 500 g. of dry silk are introduced into this solution, and left for about 10 minutes in the same. Then the temperature of the bath is gradually raised to -90 to remain about another 10 minutes in the bath. The silk need only be stirred round a few times. This stirring may be further reduced, when curved sticks are used, submerging the silk altogether in the bath.

After he treatment the silk is thoroughly rinsed and is then ready for further treatment, drying or dyeing.

I claim:

1. The process of providing artificial silk with a du l lustre which comprises introducing the .finished silk into a solution contain- C. and the silk is allowed ing a silico fluoride and heating the said solution.

2. The lprocess of providing artificial silk with a du l lustre which comprises introducing the finished silk into a, solution containing magnesium silico fluoride and heating the said solution.

In testimony whereof I aflix my signature.

Dr. CORNELIS WARNARDUS ZAIIN. 

